A Guide To Orthotic Therapy For Adult-Acquired Flatfoot

Author(s): 
Paul R. Scherer, DPM

Recommendations On Pathology-Specific Orthoses For Stage II AAF

Negative cast: podiatric AFO fabricated from a neutral cast with the supinatus reduced
Positive cast correction: perpendicular
Material: deep heel cup of 25 to 35 mm
Width: wide with medial flange
Cast fill: standard to maximum dependent on deformity
Heel skive: 6 mm
Hinges: full flexion hinges with bilateral lower leg uprights
Positive cast modification: navicular sweet spot
Rearfoot post: flat or 0/0
Top cover: full-length top cover

What You Should Know About Treating Stage III AAF

The challenges in treating stage III AAF with an orthosis are due to the reality of the foot being deformed and rigid, with seemingly intractable symptoms of pain in the medial arch.3,4 Non-surgical treatment will not reverse or improve the deformity. Treatment goals are limited to reducing symptoms and preventing greater subluxation while attempting to keep the patient ambulatory. These goals also focus primarily on immobilization that allows ambulation.

   It is therefore the goal of treatment to restrict motion in all three rearfoot joints while keeping the patient ambulatory. Restricting the subtalar joint while allowing ankle and midtarsal motion does little to relieve symptoms.10 Conversely, clinical experience suggests that controlling sagittal plane motion at the ankle but disregarding midtarsal joint motion only produces greater arthritic degeneration as the midtarsal joint dorsiflexes to compensate for the loss of the ankle sagittal plane motion. This is a plane of motion unsuited for the unstable midtarsal joint.

   The gauntlet type of AFO, which combines a custom polypropylene shell interior wrapped in a lace-up leather exterior envelope, allows restriction of motion of all three joints in all three planes without sacrificing the patient’s ability to ambulate and wear reasonable shoes. These braces are individually fabricated on a positive corrected mold of the patient’s foot from a semi-weightbearing cast with the foot at right angles to the leg in the sagittal plane.

   Although this brace has been available for more than a decade, few podiatrists or orthopedic surgeons embraced this therapy until the research of Imhauser and colleagues in 2002 demonstrated that, in comparison to other modalities, the gauntlet “completely restored the height of the arch and height of the navicular.”12

   They compared the efficacy of insole orthoses and gauntlet ankle braces by evaluating their stabilizing effect on the motion of the medial longitudinal arch and calcaneal position of six cadaveric subjects.12 Researchers simulated a flatfoot condition by sectioning the structures of the medial arch. They tested each specimen with six different devices: UCBL foot orthoses, a molded polypropylene AFO, an Arizona-type gauntlet and three prefabricated stirrup-type braces. The UCBL in-shoe orthoses provided superior restoration of both arch and hindfoot kinematics. The molded polypropylene AFO performed poorly. The Arizona-type gauntlet restored the height of the midfoot but had little effect on the orientation of the calcaneus. The prefabricated stirrup-type braces were basically ineffective in stabilizing the hindfoot and arch.

   Interestingly, in another study performed in 2003, 95 percent of patients treated conservatively with restrictive devices for adult-acquired flatfoot reported a significant reduction in symptoms.13

   The gauntlet brace that is recommended for stage III adult-acquired flatfoot must be made to specific parameters in order to have a positive clinical outcome. Accurate casting is absolutely essential if the brace is to be comfortable and produce good patient acceptance and tolerance.

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